A Plasma Display Panel (PDP) displays images including texts and/or graphics by emitting light from a phosphor by 147 nm ultraviolet rays generated when inert mixture gas such as He+Xe, Ne+Xe and He+Ne+Xe is discharged. The PDP is suitable for making a display apparatus thin and large and recent development in the PDP technology provides remarkably improved image quality. Particularly, since a 3-electrode alternating current (AC) surface discharge type PDP has wall charges accumulated in the surface during discharge and it protects electrodes from sputtering generated by the discharge, it has advantages that it requires a low operation voltage and has a long lifespan.
FIG. 1 is a perspective view showing a discharge cell of a conventional PDP.
Referring to FIG. 1, the discharge cell of a 3-electrode AC surface discharge type PDP includes a scan electrode Y and a sustain electrode Z which are formed on an upper substrate 10 and an address electrode X formed on a lower substrate 18. Each of the scan electrode Y and the sustain electrode Z includes transparent electrodes 12Y and 12Z and metal bus electrodes 13Y and 13Z having a line width narrower than transparent electrodes 12Y and 12Z and formed in one edge of the transparent electrodes.
The transparent electrodes 12Y and 12Z are generally formed of indium-tin-oxide (ITO) on the upper substrate 10. The metal bus electrodes 13Y and 13Z are generally formed of metal such as Cr on the transparent electrodes 12Y and 12Z and they reduce voltage drop caused by the high-resistance transparent electrodes 12Y and 12Z. The upper substrate 10 with the scan electrode Y and the sustain electrode Z formed in parallel is coated with an upper dielectric layer (14) and a protection layer (16). The wall charges generated from the plasma discharge are accumulated in the upper dielectric layer (14). The protection layer (16) protects the upper dielectric layer (14) from being damaged by the sputtering generated during the plasma discharge and it increases a secondary electron emitting efficiency. Typically, magnesium oxide (MgO) is used to form the protection layer (16).
In the lower substrate 18 with the address electrode X, a lower dielectric layer 22 and a barrier rib 24 are formed. The lower dielectric layer 22 and a barrier rib 24 are coated with a phosphor layer 26. The address electrode X is formed in a direction crossing the scan electrode Y and the sustain electrode Z. The barrier rib 24 is formed in the shape of stripe or lattice and it protects the discharge cell from being exposed to the ultraviolet rays and visible rays generated from the discharge. The phosphor layer 26 is excited by the ultraviolet rays generated from the plasma discharge and produces one of red, green and blue visible rays. The inert gas is injected into a discharge space formed between the upper and lower substrates 10 and 18 and the barrier rib 24.
Each pixel of the PDP includes a discharge cell having the above-described structure and represents gray level by using the visible rays emitted from the discharge cell. The discharge in the PDP causes an Electro Magnetic Interference (EMI). To block the EMI, an EMI filter is formed in the front surface of the PDP. Conventional PDPs have adopted glass filters but recent ones are mostly come with film filters.
FIG. 2 is a cross-sectional view showing one side of a conventional PDP module with a film filter.
Referring to FIG. 2, the conventional PDP module includes a panel 32, a film filter 30, a heat sink 34, a printed circuit board 36, a back cover 38, a filter supporter 40, and a grounding unit 42. The panel 32 is formed by combining the upper substrate 10 and the lower substrate 18. The film filter 30 is mounted on the front surface of the panel 32. The heat sink 34 is set up in the rear surface of the panel 32. The printed circuit board 36 is mounted on the heat sink 34. The back cover 38 is formed to surround the rear surface of the PDP. The filter supporter 40 connects the film filter 30 to the back cover 38. The grounding unit 42 is set up between the film filter 30 and the back cover 38 to surround the filter supporter 40.
The printed circuit board 36 supplies operation signals to the electrodes of the panel 32. It includes many driving units, which are not shown in the drawing, to supply the operation signals. The panel 32 displays a predetermined image in response to the operation signals from the printed circuit board 36. The heat sink 34 emits heat generated from the panel 32 and the printed circuit board 36. The back cover 38 protects the panel 32 form external impact and blocks the EMI emitted to the rear surface of the panel 32.
The filter supporter 40 electrically connects the film filter 30 to the back cover 38. The filter supporter 40 grounds the film filter 30 to the back cover 38 and also prevents the EMI emitted to the sides. The grounding unit 42 supports the filter supporter 40, the film filter 30 and the back cover 38.
The film filter 30 not only blocks the EMI but also prevents external lights from being reflected.
FIG. 3 is a cross-sectional view illustrating a structure of a conventional film filter 30.
Referring to FIG. 3, the film-type film filter 30 includes an EMI shielding film 54 formed on a first base film 50. The mesh filter 54 is formed of a conductive metal in a mesh pattern and blocks the EMI.
The mesh filter 54 is typically formed of Ag or Cu and a transparent resin 56 fills the meshes of the mesh filter 54. At the edge of the EMI shielding film 54, a filter grounding unit 52 is formed.
A second base film 60 is formed on the mesh filter 54. The second base film 60 is fixed onto the mesh filter 54 by an adhesive agent 57.
On the second base film 60, a non-reflective layer 58 for preventing external lights from being reflected is formed to clearly display images.
The filter grounding unit 52 is generally formed of the same metal as the mesh filter 54. The filter grounding unit 52, which is a hard metal, becomes a standard for alignment with the panel.
Since the film filter requires two base films to form the non-reflective layer with the mesh filter and ground the EMI blocked out in the mesh filter to the back cover through the filter grounding unit, there are problems that the production cost is high and that the panel structure is complex.